1. Technical Field of the Invention
The present invention relates to a method for automatically teaching a reference position which is the position of a disc-like object in a reference co-ordinate system including the position of the handling device which is required to be carried out at treating the disc-like object such as a semiconductor wafer and a device thereof; relates to an automatic positioning method using the method of determining a center position in the teaching and a device thereof; relates to a carrying method for automatically correcting a carrying route utilizing the positioning and a device thereof, and further, relates to also an automatic semiconductor manufacturing equipment utilizing those devices.
2. Related Art
As shown in FIG. 1 and FIG. 2, in general, a semiconductor manufacturing equipment 1 carries wafers by a carrying robot 4 from cassettes 6 in which semiconductor wafers and the like are stored on shelves to load lock chambers 8 which are the carrying ports of various kinds of treatment chambers 7, or from the load lock chambers 8 to the treatment chambers 7, or has a carrying device 2. As shown in FIG. 3, the carrying robot 4 is equipped with a carrying arm 12 which has a holding portion 14 which mounts or fixes wafers and the like and can move by extension and contraction, rotation and ascent and descent, and the motions of respective axes of the carrying robot 4 are controlled by a control portion 11. The control portion 11 memorizes the procedure and route of carrying and the co-ordinate information of carrying positions in the reference co-ordinate system containing the positional co-ordinate of the carrying robot 4 and dispatches motional orders to the respective axes of the carrying robot 4 based on it. Thereby, the carrying robot 4 can automatically carry a disc-like object such as a wafer 13 to a fixed carrying position and the control portion 11 is required to recognize the positional co-ordinates of the fore-mentioned carious instruments and wafers in the above-mentioned reference co-ordinate system respectively, to do so.
FIG. 26 shows a portion of the flow chart of the teaching step for determining the original co-ordinate at the start-up of the semiconductor manufacturing equipment 1 in a conventional carrying device 2 which is shown in FIG. 25. The “teaching” herein is a work for determining the reference position for delivering a wafer 13 or the like between the carrying robot 4 and the cassettes 6 and the load lock chambers 8, between a positioning device 10 or the like which is separately provided, if necessary.
For example, when the teaching is carried out with respect to a step of carrying the disc-like object such as a wafer 13 which is stored in the cassettes 6 to the load lock chamber 8, firstly, the temporary positional information (initial value) of the carrying robot 4 on design is inputted in the control portion 11 at the step S1, then the retaining portion 14 of the carrying robot 4 is moved little by little in a manual operation to the delivery position with the cassette 6 based on the design drawing by the step S2. However, the disc-like object remains to be mounted at the normal position of shelves in the cassettes 6 and remains in a condition in which it is not fixed on the retaining portion 14.
Then, as shown in FIG. 3, a guide jig 20 is installed on the holding portion 14 at the step S3 and it is visually confirmed whether the mounting position of the disc-like object is perfectly coincided with the holding position on design drawing or not. When it is deviated, the carrying robot is moved by rotation, extension and contraction, and ascent and descent in manual operation at the step S4, the position of the holding portion 14 is corrected to a proper position, and successively, the positional information obtained in the step S4 is transmitted to the control portion 11 at the step S5 to renew the initial positional information.
When there is no deviation in the confirmation at the step S3, the disc-like object retained is carried to the delivery position with the load lock chambers 8 at the step S6, and then it is visually confirmed at the step S7 whether the carrying position of the disc-like object is just as the design drawing or not. When there is deviation in an actual carrying position, the work returns to the step S4 and proceeds to the step S5. When there is no deviation, a series of the teaching are terminated.
Thereafter, the teaching work of the reference position is carried out one by one in accordance with the procedures from the step S1 to the step S7 between the positioning device 10 and the respective load lock chambers 8 with respect to the carrying robot 4 and between the respective load lock chambers 8 and other ports such as treatment chambers 7 with respect to the vacuum robot 31.
Further, the positioning of the disc-like object in conventional manufacturing steps is carried out at each time using the positioning device (proprietary machine) 10 as shown in FIG. 25. In the carrying device 2 as shown in FIG. 25, after the wafer 13 is delivered once to the disc rotational positioning device 10 which is separate from the carrying robot 4 in order to prevent that the locus of the wafer 13 during carrying is interfered with the cassettes 6 and the rims of respective inlets and outlets, the carrying robot 4 receives the wafer 13 again and usually carries it to an object position.
There is proposed in JP-B-7-27953 a method by which in order to improve productivity by the above-mentioned delivery step, the carrying arm of the carrying robot is moved while holding a wafer and passes a gate type positioning device which has luminescence portions 9a and light receiving portions 9b respectively and in which three sensors 9 which detect a wafer 13 with light fluxes 9c were provided to calculate the center position of the wafer. In the method, the reference holding position of a wafer is preliminarily taught, the route of the holding portion 14 is corrected from the transition quantity between the teaching position and the center position of a wafer which was detected by the fore-mentioned gate type positioning device, and the wafer is carried to an objective place without interfering with other instrument. Thereby, a time required for the delivery and reception for the positioning device 10 is shortened and the above-mentioned method contributed to the improvement of productivity.
Problems to be Solved by the Invention
However, as shown in the flow chart of FIG. 26, a conventional teaching work which was previously described is an all manual system by which trial and error are repeated using the guide jig 20 between all instruments with which the carrying robot 4 cooperates, while continuously visually confirming the position. Thus, this previous method required significant manual interaction. Since this requires continual manual work by a skilled technician, a time of one full day or more was necessary for only the carrying device shown in FIG. 25.
Further, as mentioned above, a gate type positioning device which is described in JP-B-7-275953 and shown in FIG. 27 is proposed as the positioning of the disc-like object in production, but since an initial teaching uses also the fore-mentioned conventional method hereat, trouble required for the start-up of equipment is not changed at all. Furthermore, since it is a device passing a gate, there is a problem that one device must be set by every inlet of respective load lock chambers and respective treatment chambers, and there has been a problem that since the device is a larger device than the diameter of a disc-like detected object such as a wafer, investment cost is enlarged. Further, since there is no positioning step before inserting a disc-like object into the fore-mentioned gate type positioning device, it has been required that the manual positioning which is troublesome as described above is preliminarily carried out so that the disc-like object is not collided with the device. When it is collided with the device by any chance, there were problems that dusts are generated without fail and it happens to damage the disc-like detected object.
Further, in the above-mentioned positioning device which is described in JP-B-7-275953, the judging method of a notching portion is geometrically illustrated, but a method of mathematically judging is not found yet. Accordingly, since a method of calculating a disc center by the minimum involution which is an approximation method is adopted, at least 3 of sensors 9 which are detection means are required and at least 7 points in total of at least 6 points on the peripheral rim of a disc and one point of the center of the disc holding portion must be measured. Further, since a point which exists on the peripheral rim of a notched portion and does not exist on a circumference is contained in the 6 points on the peripheral rim without fail, an accurate position is not strictly calculated and precision was bad. Further, there is proposed a calculation equation of determining the radius of a disc from 4 points on the peripheral rim which does not include the notched portion based on known Pythagorean theorem, but since the point on the notched portion cannot be excluded, the accurate radius of a disc could not be really determined.